That does not discount the threat of drink-spiking and drug-facilitated sexual assault. The number of cases involving date rape drugs may be deceiving as a vast majority of rapes go unreported, and those that are reported often are done so after a drug has left the victim's system, which limits gathering evidence through blood or urine sample testing.

"We really don't know for sure what the actual numbers are," said Dr. Susan R.B. Weiss, associate director for scientific affairs for the National Institute on Drug Abuse at the National Institutes of Health. But, she said, "drugs that are sedating drugs or incapacitating drugs probably are not that common in sexual assault.

"We really don't know the true prevalence, but we know for sure alcohol is much more common than other drugs."

And, experts note, awareness that alcohol alone may be just as debilitating can help change the conversation surrounding the dangers and the precautions needed to protect a potential victim of sexual assault.

"It's a time that, I believe, all of us need to be careful," said Dr. Corey Slovis, chair of emergency medicine at Vanderbilt University Medical Center. "The concept of trust, especially with people we don't know very well, is something that can't be counted on — especially when alcohol is involved."

Socially accepted

The social acceptance and accessibility of alcohol seems to reduce its recognition as a potential date rape drug. Its effects, however, demonstrate how it functions as one.

But as a person's blood-alcohol level rises with continued consumption, the physiological effects of alcohol — confusion, sedation and potential loss of consciousness — cause lowered inhibitions and may incapacitate a person, rendering him or her incapable of consenting to any sexual act, Slovis said.

“When it comes to date rape drugs, in the vast majority of the cases, once we start talking to an officer or we look at the case, it's going to be alcohol.”

Mike Lyttle, Tennessee Bureau of Investigation’s Nashville crime lab

It also may reduce the capacity of potential victims to physically resist a sexual attack, said Kathy Walsh, executive director at Tennessee Coalition Against Domestic and Sexual Violence.

"There are date rape drugs in circulation, and innocent women have been raped due solely to a date rape drug or a date rape drug and alcohol," Slovis said. "However, the majority, it appears, of rapes that occur with non-consenting women occur because they have been either intoxicated more than they believe or they have been given higher quantities of alcohol than they thought they had been given."

Scientific process

Data from a 2007 study for the National Institute of Justice on drug-facilitated, incapacitated and forcible rape indicate that only a small fraction (0.6 percent) of female undergraduate students who were sexually assaulted when they were incapacitated were certain they had been victims of drug-facilitated sexual assault.

Another 1.7 percent suspected they were incapacitated after having been given a drug without their knowledge.

That same study, however, indicated that the vast majority of incapacitated sexual assault victims (89 percent) reported drinking alcohol and being drunk (82 percent) before their victimization.

"When it comes to date rape drugs, in the vast majority of the cases, once we start talking to an officer or we look at the case, it's going to be alcohol," Lyttle said. "You may have things that exacerbate that, but we really don't have a smoking gun."

But there is another factor to consider: Most victims don't remember being drugged or assaulted and may not become aware of an attack until hours after it occurs. Many drugs associated with rape leave the bloodstream within hours.

Victims may also choose not to report a crime. The study for the National Institute of Justice found that only 16 percent of all rapes were reported to law enforcement. Notably, victims of drug-facilitated or incapacitated rape were somewhat less likely to report to the authorities than victims of forcible rape, the study found.

In cases where drug-facilitated assault is suspected, each toxicology screen must be done during a certain time period after the drug has been ingested in order to detect it. Victims do not have to undergo a medical exam if they do not want to report the rape to authorities.

Urine has a longer drug detection period than blood, but if a victim urinates before being examined, traces of the drug may be gone, narrowing the chance of a positive test even when drugs are involved.

Said Lyttle: "It's extremely rare that we get a case in (the TBI Nashville lab) with a sample that you actually think you have a shot."

'No way to know'

Victims will come in describing incidents that suggest they may have been drugged, but, Morante said, without the positive test, "It really is just sort of people talking ... there's no way to really know."

The problem, she said, is "none of us really knows how prevalent and what drugs are being used."

Still, simply going into a bar and having drinks should not put a person at risk for being sexually assaulted, Curtis said.

"People don't get raped because they have been drinking, because they are passed out or because they are drunk. People get raped because there is a perpetrator there — someone who wants to take advantage of them."

To protect against that, the community needs more education about bystander awareness and intervention, Curtis said. If you see someone who is vulnerable and possibly intoxicated, and you see someone who might be taking advantage of another person, step up and intervene.